When comparing Rosetta Stone vs Duolingo, the Slant community recommends Duolingo for most people. In the question“What are the best sites for learning foreign languages?”Duolingo is ranked 1st while Rosetta Stone is ranked 18th. The most important reason people chose Duolingo is:

Progress is measured gaming-like by gaining XP, leveling up and knowing how many words are learnt. Also, lessons have a limited amount of lives, which you must preserve to pass the lesson.
They use other creative gamification techniques to keep you motivated such as making wagers and improving your position on the leaderboard.

Pros

Pro

Speech recognition technology

Instead of teaching word recognition, Rosetta Stone uses speech recognition technology to make sure that students are learning to pronounce the words correctly.

Pro

Provides immersive learning without uncomfortable experiences

While trying to cary a conversation in a foreign language can be an effective way to learn, sometimes it causes a lot of stress. Rosetta Stone takes this concept and applies it to a stress free environment.

Pro

Real human contact

At the end of each lesson, students are able to review live with real teachers.

Pro

Games with other students

When learning another language, a learner from that language can be invited to play a game for mutual learning purposes. Unfortunately, Rosetta Stone hasn't spread very much to countries outside of the US, so this game system isn't very developed yet.

Pro

Motivates through creative gamification

Progress is measured gaming-like by gaining XP, leveling up and knowing how many words are learnt. Also, lessons have a limited amount of lives, which you must preserve to pass the lesson.They use other creative gamification techniques to keep you motivated such as making wagers and improving your position on the leaderboard.

Pro

Generous free plan

Duolingo is completely free to use, with no features limited to upgraded accounts. If you want to go ad-free, the cost is $12.99/month.

Pro

Engaging learning method

Each lesson uses a variety of different learning methods to keep it interesting and fun.The lessons are short so you aren't forced to focus for long periods of time.

Pro

Friendly, active community

There is a discussion board available on the site, and a really active community on reddit in r/duolingo (30k + members). Everyone is friendly and happy to help or offer support.

Pro

Has a mobile app

Pro

Extensive

Duolingo is exceptionally thorough when it comes to teaching the nuances of language. It has plenty of audio material, articles to translate, and a cooperative development made by users.

Pro

Frequently adding new languages

You can check out the courses page to see what languages are "hatching" (being developed) and what languages are in beta.

Cons

Con

Makes no use of native language

While Rosetta Stone tries to emulate "learning by immersion," many people find the inability to find direct translations of words to be an unnecessary an ineffective part of the program.

Con

Uses the same course for learners of different nationalities

For a user learning English, the course will be the same whether they are Chinese, Russian, Italian, etc.. While this is a good way for the company to remain efficient, many cultural differences are overlooked.

Con

Inconvenient meeting times for teachers

For users in the US, it can be easy to find a teacher to work with. In any other country, it can be extremely difficult to find an available teacher because of the differences in timezones.

Con

Mobile app is less beneficial because it's too easy

Some of the games available on the mobile app are different from that on the desktop version, and are oversimplified/make it very easy to guess.

Con

Little production of target language

Duolingo focuses heavily on reading comprehension and translation into one's own language rather than encouraging production of text/speech in the target language.

Con

Available languages are predominately European

Duolingo teaches 23 languages from English at the moment: Latin American Spanish, French, German, Italian, Portuguese, Dutch, Swedish, Irish, Turkish, Danish, Russian, Norwegian, Esperanto, Ukrainian, Polish, Welsh, Greek, Romanian, Hungarian, Hebrew, Swahili, Vietnamese and Japanese (the last currently only on the app). Popular non-European languages such as Mandarin and Arabic are not currently available (although Korean and Indonesian are in development).

Con

The health system on the IOS app disrupts learning

5 mistakes and you're out, unless you pay, wait several hours, or use a special review that currently doesn't let you choose what to review. Especially terrible if you're learning multiple or more difficult languages.

Con

The hype in the community creates false ideas about what level Duolingo gets you to

Duolingo is a good tool for a beginner, and a good supplement to other resources. But it cannot get you from zero to understanding natives, tv, and books; and their "do the reverse tree and just speak" is usually not the correct answer to "what should I do after finishing the tree".